Field of the Invention
This invention relates to an absorbent pad, such as a diaper, including an odor control material.
Background of the Related Art
Disposable diapers are produced in a continuous process similar to an assembly line and can run at speeds of up to 1200 feet per minute and produce around 1000 diapers per minute. The process starts at the hammer-mill, where a sheet of pulp board is fed into a rotary hammer-mill and is converted into individual cellulose fibers (from 2.0 to 2.7 mm in length). These fibers are transported via an air stream into a forming drum made of individualized or continuous perforated screen pockets having a vacuum underneath to dissipate the air thus forming a cellulose batt of fibers. The drum former usually holds between 8 to 12 pockets (or individual diaper lengths), depending on diaper size and the diameter of the drum.
As these cellulose fibers are produced, they are mixed with a super-absorbent within the drum former. The superabsorbent particles (SAP) are measured by either gravimetric or volumetric feeders. The flow rate of these particles is controlled with great accuracy and the SAP is then fed into an airstream and combined in an admixture with the cellulose fibers prior to being formed into an absorbent batt in the drum former.
An odor control material (OCM) can be added to the absorbent core with a similar secondary apparatus, or combined with the SAP to form only one stream. The air forming technology used in the drum formers will allow either the OCM particles or the SAP to be strategically placed in the batt of fibers in either the X-Y plane, in the Z direction, or have them homogeneously mixed with the cellulose fibers.
The mix of cellulose fibers, SAP, and OCM being formed in the drum is called “the absorbent core”. Once the pad is formed, a layer of tissue or light weight spunbond nonwoven is placed on the top, bottom or around the whole pad. A special adhesive can be used to adhere these layers to the absorbent core. This adhesive and the nonwoven provide integrity to the absorbent core and assist in containing the SAP and the OCM from coming out of the absorbent core during the process and while in use. The pad is then compressed using a de-bulking roll, or embossed with an embossing patterned roll.
In the next process steps, a polyethylene film or nonwoven film laminate is added at the bottom of the pad to provide the backsheet, and a non-woven material is added on top to provide the topsheet material or liner which is next to the skin. Spandex filaments of elastic are added at the edges of this structure in between the backsheet and topsheet to provide the leg elastic components. Then the leg cuff nonwoven material with additional Spandex filaments are added to the edges of the diaper on top of the topsheet to provide this containment feature. This composite structure is called the diaper “sausage”.
A film frontal tape or nonwoven loop target material is adhered to the polyethylene film or nonwoven film laminate backsheet, using a cut and place applicator. Fastening tapes made with either positioning adhesive or with mechanical fasteners are added to the backsheet. In order to adhere all these materials, hot melt pressure sensitive adhesives (PSA) are used in the form of individual lines, slot coating or melt-spray. Two different types of pressure sensitive adhesives are used: one designed for the elastic components, and one used for laminating and attaching the nonwoven components of the diaper.
These fastening devices can either be attached directly to the diaper “sausage” as described above, or pre-attached to elastomeric materials to comprise the stretch “ear” portion of the diaper. The elastomeric side panels or “ears” can be adhered via PSA's, or via ultrasonic thermal bonding of the materials the combined topsheet and backsheet portion of the diaper sausage.
All of the components that are added to the diaper are registered in the machine direction usually by a vision inspection system to guarantee the proper placement of the components onto the diaper “sausage”.
The diaper “sausage” is then cut into individual diapers and bi-folded or tri-folded prior to being inserted into a vertical or horizontal stacker. Here it is counted into whatever number of diapers is to be inserted into a diaper bag, which is then sealed for packing into corrugated cartons.